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1ms cycle with CPU312 IFM

Created by: Eyal at: 12/23/2013 11:52 AM (6 Replies)

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12/23/2013 11:52 AM	Rate (0)
Eyal Member Joined: 7/24/2012 Last visit: 12/24/2020 Posts: 5 Rating: (0)	How can i make 1 ms cycle in the program? Thanks Eyal

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12/23/2013 7:55 PM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 3/3/2021 Posts: 4206 Rating: (791)	Eyal How can i make 1 ms cycle in the program? Thanks Eyal It is not possible to make accurite 1ms cycles. If you used cyclic interrupt OB, ypu will found the min. cycle is 100 msec.
	Ayman Elotaify
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12/23/2013 9:09 PM	Rate (0)
Gerdoo Experienced Member Joined: 4/15/2008 Last visit: 4/12/2019 Posts: 23 Rating: (2)	From configuration stand point, YES you can. You canmodify the cycle time of an Cyclic Interrupt OB (like OB35)to 1 ms. But the problem is with a CPU like this, it can not handle such a fast driven interrupt and you will get the "cycle time exceeded error". I beleive the best you can get with 312 is between 10-20 ms depends on the program load.

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12/24/2013 6:54 AM	Rate (0)
Eyal Member Joined: 7/24/2012 Last visit: 12/24/2020 Posts: 5 Rating: (0)	Thank You.

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12/24/2013 8:02 AM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 3/3/2021 Posts: 4206 Rating: (791)	Hello, After revise again, yes you can do it with OB35 with 1msec cycle. But keep in mind that in case of the processing time of code you will write in OB35 will exceed 1msec, The CPU will enter the STOP mode. Thus because, each 1 msec, you will need to call OB35 once again although you did not reach to the end of OB35 of last call yet! So, when you design a program, you have to think how will you operate and manage these OBs and also OB1 (Cyclic OB). I do not know your application, but if you need to generate a train of pulses for instance (once each 1 msec), then this way is not suitable. There are other ways. So, it will be more helpful for you if you told us what do you want to do each 1 m sec to allow us to find the most suitable solution. Hope this helps.
	Ayman Elotaify
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This contribution was helpful to 2 thankful Users dchartier Marcjan

12/25/2013 8:05 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (989)	Eyal How can i make 1 ms cycle in the program? Thanks Eyal The CPU312 IFM is very old and very slow. There is no good chance to work with 1ms scan. Not with OB35, also not with OB1 and of course not with a timer. My advice, if you really need to be so fast, change PLC Type.
IBN-Service Posts: 8946 Rating: (989)
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12/26/2013 2:22 PM	Rate (0)
Eyal Member Joined: 7/24/2012 Last visit: 12/24/2020 Posts: 5 Rating: (0)	Thank You All I will change the PLC.

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